N-Type organic field-effect transistors with high electron mobilities based on thiazole-thiazolothiazole conjugated molecules

Two novel thiazolothiazole derivatives with trifluoromethylphenyl groups were synthesized and characterized by differential scanning calorimetry, X-ray single crystal analysis, UV-vis absorption spectroscopy, cyclic voltammetry, field-effect transistor (FET) characteristics, and X-ray diffraction. The FET characteristics of thiazole-thiazolothiazole derivatives are strongly dependent on the nitrogen positions. The derivative with a 2-(4-trifluoromethylphenyl) thiazole unit afforded a high performance FET device that showed a high electron mobility of 0.12 cm² V^-1 s^-1 with a bottom contact configuration. Moreover, with a top contact configuration, high electron mobilities of 0.24-0.64 cm² V^-1 s^-1 and low threshold voltages of 18-24 V depending on the surface modification were achieved. The relationship between molecular structure, molecular packing, electrical characteristics, film structure, and FET performance were investigated.